The present invention relates to insulation displacement terminals used in electrical connectors, and more particularly, to an insulation displacement terminal that facilitates reduction in size and cost and assembly of electrical connectors.
An insulation displacement terminal is widely known as useful in effecting connections between electrical wires and opposing connectors without requiring the soldering of the wires to terminals. Such terminals include slots in which the wires are pressed, and the sides of the slot bite into the outer insulation covering of the wire and into contact with the inner conductive core of the wire to obtain a reliable and a gas tight connection. Such insulation displacement type terminals are useful in reducing the size of the connector and in weight reduction and in reduction in cost of the connector. Insulation displacement terminals are also renown for their ease and superiority of assembly and reliability. Therefore, insulation displacement type terminals have been extensively used as a female terminals of electric connectors.
FIG. 12 illustrates a known insulation displacement type terminal which reduces the amount of material used and which is inexpensive to produce and easy to assemble. FIG. 13 illustrates a known female connector into which such a insulation displacement type connector is assembled, as is shown in Japanese Utility Model Application Laid-Open No. Hei 2-101468.
The terminals 150 shown in this known terminal and connector are of a female type and are provided with a pair of wire-contacting elements, or slotted tabs, 151 & 152 that form conductive terminal portions and are also provided with two terminal contact portions 153 & 154 that are positioned parallel to each other to form a pair of terminal beams. The wire-contacting elements 151 & 152 are connected to each other through a linking, or connecting, body portion 155 which is shown as parallel with the terminal contact portions 153 & 154. In mating with an opposing connector, a male terminal 160 of the opposing connector (not shown) includes a pin terminal that is inserted in between the connecting body portion 155 and the terminal contact portions 153 & 154. The wire-contacting elements 151 & 152 have respective slots 511 & 521, that receive an electrical wire 156 therein. Displacement of the insulation of the wires occurs when the wires are placed into the slots 511 & 521 so that the wire 156 is electrically connected to the terminal 150.
As shown in FIG. 13, the terminal 150 is assembled into a connector housing 170. A plurality of terminal-receiving recesses 171 are arranged in the connector housing 170 and receive wires 156 in a parallel arrangement so that a variety of female connectors containing different numbers of wires and terminals may be formed.
As shown in FIG. 14, for example, such a terminal 150 is manufactured by punching out a conductive plate 501 to obtain the base shape of the terminal 150 and thereafter bending parts thereof to form the final terminal 150. Thus, the width W1 and the width of the connector housing recess 171 are identical with each other. As a result, the overall width dimension W1 of the terminal 150 is reduced to where it is substantially the same as that of each of the wire-contacting elements 151 & 152 so that the material of the conductive plate 501 is effectively used in the construction of the terminal 150.
In this regard, for example, a female terminal 150A having the shape shown in FIG. 15 takes a form such that the terminal contact pieces 153 & 154 are arranged on both sides of the wire-contacting elements 151. Accordingly, the overall width W2 of the terminal 150A is greater than the width W1 of the two wire-contacting elements 151 & 152. Therefore, the conductive material of the terminal 150A is not economically utilized in such a terminal construction.
Returning to FIG. 12, and the terminal 150 illustrated therein, although the conductive material is effectively utilized to effectively attain a reduced size and reduced weight aspects, the terminal 150 suffers from the following problems. First of all, there is a room to further improve the efficiency of utilization of the conductive material that makes up the terminal. Namely, when produced as a mass in conjunction with a carrier strip, such as that shown in FIG. 14, a plurality of terminals 150 are connected in chain-like arrangement to each other by a terminal carrier strip 502. However, the portion of the conductive plate 501 corresponding to the spacing with a width of W3 between the adjacent terminals 150 of the carrier strip 502 must be punched out. This portion is sent to scrap and is wasted in the manufacture of the terminals.
This punched-out portion corresponds to the interval, or spacing, that is disposed between the respective terminal-receiving recesses 171 of the connector housing 170. This portion is required to align the respective terminals 150 on their pitch P1 with their respective connector housing recesses 171 when the terminals 150 are simultaneously assembled from their carrier strip 502 into the connector housing 170 and its associated recesses 171. Secondly, a problem occurs the ability to connect the wire(s) 156 to the terminal 150. Because the terminals 150 are received in a like plurality of respective connector housing recesses 171, the wires 156 are simultaneously inserted from above the terminals into the two slots 511 and 521 that are formed in the wire-contacting elements 151 & 152 to obtain the desired pressed, insulation-displacement connection. However, as shown in FIG. 13, a space .varies. having a desired interval is required between the wire-contacting element 151 located on the front end side of the wire 156 and a front end face 711 of the connector housing recess 171. This is because a desired length of the wire with its insulative covering 561 must be left at the front end of the wire 156 and also that it is necessary to keep a good working space of the connector housing into which a terminal press jig may be inserted. With such a space, it is possible to perform a good press connection of the wire 156 to the terminal 150.
However, with the terminal having such a structure, the interval between the wire-contacting elements 151 & 152 is substantially the overall length of the terminal, and in instances where the length of the connector housing recess 171 is identical with the length of the terminal, it becomes difficult to keep such a space in the structure. For this reason, and as shown in FIG. 13, the length of the receipt recess 171 must be longer than the length of the terminal 150, typically by the length of the space. Accordingly, it will be understood that although the terminal 150 per se may be reduced in size, the overall connector housing 170 is not so reduced in size.
Thirdly, it is important and desired to keep an effective contact length between the female terminal 150 and opposing contacts 160 of an opposing male terminal. In the known structure illustrated, the effective contact length of the terminal 150 is shortened as the overall length L of the female terminal 150 is shortened and the female terminal is reduced in size. For this reason, in this structure, there is a limit to the reduction in size that can be attained with such a terminal 150. Fourthly, a problem occurs with the three-point contact terminal that is established by the terminal contact pieces 153 & 154 and the body portion 155 of the terminal. In order to attain good and reliable three-point contact with this known terminal 150, it is necessary to perform extremely high precision machining in comparison with a terminal that has a two-point contact arrangement by clamping the associated terminal on both sides.
The present invention is directed to a terminal construction that avoids these shortcomings and overcomes these disadvantages.